The invention relates to digital road maps and, more particularly, to a method for producing highly precise digital road maps for use with vehicle applications.
The current generation of digital maps all use the so-called xe2x80x9csegment and nodexe2x80x9d approach, wherein every road segment begins and ends at a node. Many attributes of the road can only be changed at the nodes, and all intersections are described as nodes. The nodes represent a physical reality, in other words, the place at which something in the road network actually changes. For example, nodes may be start points and end points of a bridge, while the segment is the actual distance traversed by the bridge. Current digital maps of this type are commercially available from companies such as Navtech, TeleAtlas and ETAK.
In real-life, however, roads themselves do not intersect at points. The center lines of the vehicle lanes in a road may intersect at a point, but using many nodes per intersection is inconsistent with current models, as well as being very complex.
There is therefore needed a highly precise digital road map and method of producing same which can provide precise details of the lane positions and other attributes. Such highly precise road maps are necessary for the next generation of applications of these maps within the vehicle, such as control systems for the vehicle based on the maps.
The present invention meets these needs by providing digital maps produced by representing the road and lane network as a set of geometric shapes (such as lanes) that are associated with traditional nodes and segments for indexing purposes only. In this representation, the nodes and segments have no physical meaning with respect to the map.
According to the present invention, the map representation uses segments and nodes merely as indexes into a more complex structure. Advantageously, branch and merge points of the road network are defined not by a physical structure but by the divergence of actual, statistical paths of vehicles. In this regard, Applicants advantageously define a path (segment) as the root of a group of people, all traveling from point A to point B, where point B is indicated not by a defined physical location, but rather by the driver""s thought processes with respect to operation of the vehicle. In this manner, the respective points such as point B are reflected by the driver""s driving behavior as measured via the driving dynamics and the vehicle location relative to fixed landmarks.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.